Projectile having changeable outer form

ABSTRACT

An explosive projectile member comprising a flexible explosive enclosed in a flexible envelope or casing that enables the whole projectile to change its size and shape from the condition that it was in before launching to another condition after launch. The projectile member is of such construction that it can be compressed to such an extent as to enable it to be placed in a narrow pocket in a mother projectile and/or can be expelled from a short firing tube. After the projectile member has been expelled it is spread out or developed by means of the air drag and elastic forces assisted by additional resilient means provided in the elastic casing.

[ Aug. 7, 1973 United States atet [191 Walde [5 PROJECTILE HAVING CHANGEABILIE Primary Examiner-Benjamin A. Borchelt OUTER FORM Assistant Examiner-J. V. Doramus 75 Inventor. Attorney-Eric Y. Munson and Robert W. Fiddler et Erik B. Walde, Esl zilstuna,

Sweden [73] Assignee: Forenade Fabriksverken,

Eskilstuna, Sweden Oct. 6, 1971 An explosive projectile member comprising a flexible Filedi explosive enclosed in a flexible envelope or casing that enables the whole projectile to change its size and Appl. No.: 186,943

shape from the condition that it was in before launching to another condition after launch. The projectile member is of such construction that it can be compressed to such an extent as to enable it to be placed in a narrow pocket in a mother projectile and/or can be expelled from a short firing tube. After the projectile member has been expelled it is spread out or developed by means of the air drag and elastic forces assisted by additional resilient means provided in the elastic casmg.

0941 74 m FAR .6 u/ 2 .0 n1 mh c r "a "e as m cm t8 .mF UN 55 References Cited UNITED STATES PATENTS 2,923,237 2/1960 Bliekamp................................ 102/8 8 Claims, 4 Drawing Figures OTHER PUBLICATIONS Stan Green Training Manual,

MB Associates, San Ramon, California, September, 1970, p. 6.

PATENTED A53 7 i973 INVENTOR.

ERIK B. WALDE ERIC Y. sumsm and mom-1m w. FIDDLIJR ATTORNEY PROJECTILE HAVING CHANGEABLE OUTER FORM BACKGROUND OF THE INVENTION The invention relates to explosive projectiles of the type having disk-shaped splinter-emitting concave or convex surfaces of the type shown, for example, in US. Pat. No. 2,972,949. The purpose of such a surface is to obtain an even or homogeneous splinter distribution focussed into useful directions only. Ordinary mortar or ordnance ammunition is inefficient and is not economical because about half of the splinters are thrown straight up in the air or straight down into the ground for projectiles exploding upon target impact. The main problem that the present invention seeks to solve is how to launch bodies having such splinter-emitting surfaces, and the invention features a structure that after ejection forms a larger diameter than the ejection tube from which it was launched.

The shape and size of known grenades and splinter surfaces are mainly determined by the shape of the projectile and are usually quite stiff. This shape is dependent upon such details as fuse design and external ballistic requirements. It has hitherto proved to be difficult to give the envelope or jacket surface of an explosive projectile such a shape that emitted splinters attain a distribution that can be obtained by fragmentation mirrors. Conventional grenade splinters usually hit the ground in some zones displaying a high splinter density followed by other zones where the splinter density is rather low. The most serious limitation is that the diameter of an explosive member at the firing moment actually ought to be larger than the diameter of the projectile from which it was launched.

SUMMARY OF THE INVENTION The invention relates to an explosive projectile member to be launched from an ejection tube, comprising a ductile or flexible envelope which encloses a ductile or liquid explosive, the wall of the envelope containing splinter-producing bodies. The envelope is expandable to form a disk or saucer-like body having a considerably larger diameter than the bore of the ejection tube from which it is ejected, and the envelope is also compressible by being bent or folded so as to allow it to be inserted in the ejection tube. A circular plate or disk, carrying the ignition means has a somewhat smaller diameter than the bore of the ejection tube and constitutes a protective body for the rest of the folded and compressed envelope and the explosive located therein in front of the plate.

One example of the wide use of the invention is a conventionally launched shell that after flight, digs itself down into the ground at impact. The impact face of the grenade ignites a charge ejecting an enclosed ductile projectile rearwardly. The projectile member is first developed by the air drag and inertia forces, turns around during flight and descends to a fuse-set proper height for an explosion to be released. Through the use of a projectile having a changeable outer form according to this invention, an economical distribution of splinters over the ground surface will be obtained. In comparison with ordinary mortar shells having impact fuses the splinter distribution will be considerably improved. In another example of the field of use, small projectiles can be packed into a mother projectile, each of said small projectiles being protected by two semispherical shells located in storage spaces for the smaller projectiles in the grenade shell body. The smaller projectiles are released for example, by discarding a cover in the rear of the shell. Centrifugal force due to rotation serves to eject and develop the smaller projectiles and parachutes of different size will give said projectiles a vertical distribution during descent. Other types of retarding means can be arranged, such as a number of braking or steering fins such as for example are used on a badminton bird or rotochute blades.

DESCRIPTION OF THE llNVENTION Reference is to be had to the accompanying drawing in which an illustrative emodiment of the invention is shown and in which FIG. ll shows in section, an explosive member of the character described packed into a firing tube;

FIG. 2 shows the explosive member in a half-way spread out position;

FIG. 3 shows the explosive member in section and as fully developed, and

FIG. 4 shows another embodiment fully developed and as seen from below.

An ejection tube indicated at 1, contains in its bottom a propelling charge 2 and initiating means for the ejection of an enclosed explosive projectile member 3. This member consists of a fixed pre-fragmented plate 4 which is integral with a thick-walled envelope 5 of elastic material such as latex rubber having a number of embedded spherical splinters 5a. The envelope part has a thin cover 6 fixed to the edge of the part 5, said cover consisting of a thin membrane such as textilereinforced rubber. The plate 4 and the two parts 5 and 6 enclose an elastic, preferably liq uid explosive charge 7, such as described for example in US. Pat. No. 3,419,443. An igniter having a delay charge 8 is fixed in the plate 4. A bent resilient wire or tubular arrangement 10 is located along the transition between the thick part 5 and the thin part 6 of the envelope. The resilient power can, if needed, be further augmented through the embedding in the thick envelope wall 5 of a number of radially extending sheet metal elements 11 fixed to the plate 4. In an alternative embodiment the thick envelope wall 5 may contain a pre-fragmented resilient metal wire 12 (FIG. 4) starting from the plate 4 and as formed as a spiral that ends at the periphery of the thick envelope part 5. The spiral is able to expand the projectile member, the wire 12 upon detonation being divided into a number of splinters, thus increasing the splinter action.

In operation, the projectile to be launched is compressed and is squeezed into the ejection tube as shown in FIG. 1. The propelling charge 7. is fired and the projectile leaves the projection tube and it soon starts to develop its increase in size with the aid or air drag and inertia forces. The auxiliary embedded resilient power makes the projectile member rapidly spread out and reach its final shape with full diameter. Due to the low location of the center of gravity the projectile member will adjust its orientation in the air and if the fuse is set for a suitable delay, the projectile member will be made to explode at such an altitude that an optimum distribution of the splinters is obtained.

Other combinations of projectile members according to the invention are possible as will appear to those skilled in this art.

What I claim is:

1. An explosive projectile member adapted to be launched from an ejection tube and comprising:

a. an envelope composed in part of a ductile material easily and compressibly deformable and containing splinter-producing bodies;

b. a ductile explosive lodged within the envelope;

0. an integral part of the wall of the envelope being shaped as a plate, and said plate having a smaller diameter than the bore of an ejection tube from which the projectile is to be launched;

d. means for initiating said explosive, said means being supported by said plate;

e. to expand said envelope to an original nominal size which is larger than its deformed compressed condition necessary to permit it to be inserted into said tube.

2. An explosive projectile member, according to claim 1 including a resilient wire and tube means located along the periphery of the envelope as the body is seen in its expanded condition.

3. An explosive projectile member, according to claim 1, including a number of radially directed resilient members fixed to the plate.

4. An explosive projectile member, according to claim 1, wherein the envelope is substantially in the shape of a covered saucer, the bottom of which has a thicker wall than the cover top, with the relative weights such as to locate the center of gravity closer to said bottom, below the horizontal median plane, and the thicker wall contains splinter-producing bodies.

5. An explosive projectile member adapted for projection from an ejection tube, said member having a base wall composed of relatively thick material in which a plurality of splinters are embedded, said body including a centrally located relatively stiff disk, said disk being of less diameter than the diameter of an ejection tube with which the projectile is to be used, the projectile member including a relatively thin and flexible and compressibly deformable cover member peripherally attached to the periphery of the base wall, an explosive charge contained between the base wall and the cover member, and resilient means contained in the base wall and serving to restore the compressed deformable cover member to original undeformed condition, to widen the diameter of the base wall and its attached cover member to nonnal full uncompressed condition when the projectile leaves the ejection tube.

6. An explosive projectile according to claim 5, wherein the resilient means for expanding the body includes a plurality of flexible radial ribs embedded in the base wall.

7. An explosive projectile according to claim 5, wherein the resilient means includes a flexible spiral starting at the center of the base wall and terminating at the periphery thereof.

8. An explosive projectile, according to claim 5, in which the relative weights of the base wall and of the cover member and of the contained elements being such as to locate the center of gravity below the horizontal median plane, so the projectile is aerodynamically stabilized. 

1. An explosive projectile member adapted to be launched from an ejection tube and comprising: a. an envelope composed in part of a ductile material eAsily and compressibly deformable and containing splinter-producing bodies; b. a ductile explosive lodged within the envelope; c. an integral part of the wall of the envelope being shaped as a plate, and said plate having a smaller diameter than the bore of an ejection tube from which the projectile is to be launched; d. means for initiating said explosive, said means being supported by said plate; e. to expand said envelope to an original nominal size which is larger than its deformed compressed condition necessary to permit it to be inserted into said tube.
 2. An explosive projectile member, according to claim 1 including a resilient wire and tube means located along the periphery of the envelope as the body is seen in its expanded condition.
 3. An explosive projectile member, according to claim 1, including a number of radially directed resilient members fixed to the plate.
 4. An explosive projectile member, according to claim 1, wherein the envelope is substantially in the shape of a covered saucer, the bottom of which has a thicker wall than the cover top, with the relative weights such as to locate the center of gravity closer to said bottom, below the horizontal median plane, and the thicker wall contains splinter-producing bodies.
 5. An explosive projectile member adapted for projection from an ejection tube, said member having a base wall composed of relatively thick material in which a plurality of splinters are embedded, said body including a centrally located relatively stiff disk, said disk being of less diameter than the diameter of an ejection tube with which the projectile is to be used, the projectile member including a relatively thin and flexible and compressibly deformable cover member peripherally attached to the periphery of the base wall, an explosive charge contained between the base wall and the cover member, and resilient means contained in the base wall and serving to restore the compressed deformable cover member to original undeformed condition, to widen the diameter of the base wall and its attached cover member to normal full uncompressed condition when the projectile leaves the ejection tube.
 6. An explosive projectile according to claim 5, wherein the resilient means for expanding the body includes a plurality of flexible radial ribs embedded in the base wall.
 7. An explosive projectile according to claim 5, wherein the resilient means includes a flexible spiral starting at the center of the base wall and terminating at the periphery thereof.
 8. An explosive projectile, according to claim 5, in which the relative weights of the base wall and of the cover member and of the contained elements being such as to locate the center of gravity below the horizontal median plane, so the projectile is aerodynamically stabilized. 